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Cylinder bores and crank journals :- rust removal ?

Posted: Sun Oct 27, 2019 8:45 pm
by 30EK42
I've just aquired the bottom end of an early 3.9 Efi engine.
The engine was stripped and chucked into boxes for reasons which so far remain unknown.
But by the looks of things the pistons/rods were stored somewhere relatively dry.
The block and crank were by the looks of it stored somewhere on the damp side, resulting in an unhealthy layer of rust all over the crank and also on most of the cylinder bores.
So my first priority is to remove the rust from the vital areas so that I can get a better idea of the condition of the engine prior to it being stripped.
I think that I can remember being told to use sandpaper for this because it's softer than emery cloth or production paper (wet and dry paper) and will remove the rust without removing any good metal.
But my memory is pretty hazy about this advice, any input about the most non-damaging method of removing the rust would be appreciated.
I'm aware that if the rust pitting is too severe then a rebore and regrind might well be required but I live in hope

Re: Cylinder bores and crank journals :- rust removal ?

Posted: Mon Oct 28, 2019 1:51 pm
by harvey
I'd buy a honing tool to do the bores, and wet and dry on the crank journals. Rolls Royce used to leave their new engine blocks outside until they got a coating of rust on the bores and then hone them before use. They used to say that the small pits caused by the rust in the bore helped retain tiny amouts of oil.

Re: Cylinder bores and crank journals :- rust removal ?

Posted: Thu Oct 31, 2019 10:13 pm
by SimpleSimon
RR did that to allow all the casting stresses out of the block before machining :)